A kind of steel plate-concrete composite cable tower crack resistance rheological modification functional material, its preparation method and application

Abstract

This invention discloses a crack-resistant rheologically modified functional material for steel-concrete composite cable towers, its preparation method, and its application. The crack-resistant rheologically modified functional material of this invention comprises 1-10 μm ultrafine light-burned magnesia expandable material, 15-30 μm medium-fine light-burned magnesia expandable material, 30-100 μm medium-coarse calcareous expandable material, 0.1-2 μm fly ash microspheres, 0.02-0.05 μm nano-silica, and an anti-agglomeration regulating material. The anti-agglomeration regulating material is composed of a zirconium aluminate coupling agent and hexadecyltrimethylammonium bromide. This crack-resistant rheologically modified functional material is applied to the concrete of ultra-high strength steel-concrete composite cable tower structures. Concrete prepared using the crack-resistant rheologically modified functional material of this invention exhibits low viscosity, good anti-segregation properties, and volume stability, achieving a synergistic unity of rheological modification and crack-resistant expansion in the concrete of ultra-high strength steel-concrete composite cable tower structures.

Description

Technical Field

[0001] This invention belongs to the field of construction technology of ultra-high strength steel plate-concrete composite cable tower structure. Specifically, it relates to a crack-resistant rheological modified functional material for steel plate-concrete composite cable towers, its preparation method and application. Background Technology

[0002] Cable towers are crucial and irreplaceable load-bearing components of cable-stayed bridges such as suspension and cable-stayed bridges, bearing enormous compressive and bending loads during bridge construction and operation. Compared to steel cable towers, steel-concrete composite cable towers have higher compressive and bending stiffness and better wind resistance; compared to concrete cable towers, steel-concrete composite cable towers not only have higher load-bearing capacity and lower structural self-weight, but also have a high degree of industrialization in manufacturing, resulting in lower construction difficulty, intensity, and labor requirements at the bridge site, and are increasingly being adopted by large-scale bridge projects.

[0003] As a steel-concrete composite cable tower structure that withstands enormous compressive and bending loads, the inner wall of the steel plate is equipped with a large number of shear connectors such as studs and horizontal stiffeners, which hinder the flow of concrete. The excessively high viscosity of high-strength concrete is prone to air pockets due to these obstacles, resulting in incomplete compaction during pouring. The yield stress of ultra-high-strength concrete mixtures, characterized by high powder content and low water-cement ratio, is relatively low, making it prone to segregation, stratification, and laitance, creating weak points at the joint surfaces of the segmented cable towers. The fully enclosed and strongly constrained nature of steel-concrete composite cable tower structures, which prevents moist curing, along with the high content of cementitious materials, high sand ratio, and high paste-aggregate ratio of the internal high-strength concrete, leads to significant risks of shrinkage, debonding, voids, and even cracking. Improving the compatibility between concrete and steel, effectively reducing the limitations of concrete material properties on the performance of steel, and developing crack-resistant rheological modification functional materials suitable for ultra-high strength steel plate-concrete composite cable tower structures, so that the prepared concrete has the characteristics of low viscosity, good anti-segregation and moisture-proof self-expansion properties, are currently hot topics in the construction field of steel plate-concrete composite cable tower structures.

[0004] Chinese patent CN 120229900A discloses a self-compacting concrete additive for ultra-large diameter steel pipes used in ultra-high cable towers, along with the concrete structure and construction method. This additive is prepared by combining 50%–60% calcium-magnesium composite expansive agent, 2.5%–4.5% hydration temperature rise inhibitor, and 35.5%–47.5% rheology modifier, addressing the issues of construction viscosity and shrinkage voids in steel pipe self-compacting concrete. While this self-compacting concrete additive shows some effectiveness in ultra-large diameter steel pipes with minimal internal obstruction, its application is less successful in steel plate-concrete composite cable tower structures with numerous shear-resistant connectors on the inner wall of the steel plate, resulting in many flow obstruction points. Furthermore, the calcium-magnesium composite expansive agent used in this self-compacting concrete additive is a compound of conventional expansive materials, and its expansion process is relatively poorly matched with the shrinkage process of the cable tower structure concrete, thus failing to completely solve the problem of moisture-free self-shrinkage voids in steel plate-concrete composite cable tower structures.

[0005] Chinese patent CN 113387612A discloses a viscosity-reducing and reinforcing crack-resistant agent and its preparation method. The agent is prepared by combining 30-60% modified magnesium oxide expansive agent, 5-20% synthetic fiber, 10-40% viscosity-reducing component, and 20-50% reinforcing component. This method regulates the adsorption characteristics of the magnesium oxide expansive agent on the water-reducing agent by forming a polymethylsiloxane film on its surface, thereby reducing the increase in concrete viscosity caused by the high water absorption of lightly calcined magnesium oxide. However, the polymethylsiloxane film easily causes the magnesium oxide expansive agent to agglomerate due to mutual adsorption, and it does not fundamentally solve the problem of easy slurry segregation caused by the irregular wetting angle of the magnesium oxide expansive agent.

[0006] Therefore, it is of great significance to research and develop a multifunctional material that can effectively ensure the expansion performance of calcium-magnesium composite expansion material, guarantee the moisture-free self-expansion performance of ultra-high strength concrete in steel plate-concrete composite cable tower structures, reduce the viscosity of ultra-high strength concrete slurry, ensure the compactness of ultra-high strength concrete in steel plate-concrete composite cable tower structures, and improve the overall quality of ultra-high strength concrete in steel plate-concrete composite cable tower structures. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a crack-resistant rheologically modified functional material for steel-concrete composite cable towers, its preparation method, and its application. This material solves the prominent risks associated with high construction viscosity, incomplete compaction, segregation, shrinkage, and void formation in ultra-high strength steel-concrete composite cable tower structures. The prepared concrete exhibits lower viscosity, good anti-segregation properties, and volume stability, achieving a synergistic unity between rheological modification and crack-resistant expansion in ultra-high strength steel-concrete composite cable tower structures.

[0008] To solve the above-mentioned technical problems, the specific technical solution of the present invention is as follows:

[0009] A crack-resistant rheological modification functional material for steel plate-concrete composite cable towers comprises the following components in parts by weight:

[0010] 25-35 parts of ultrafine lightly calcined magnesium expanded material

[0011] 18-25 parts of medium-fine light-burned magnesia-based expanded material

[0012] 20-30 parts of medium to coarse calcium expanded material,

[0013] 22-28 parts of fly ash microspheres

[0014] 10-15 parts of nano-silica

[0015] 1-3 portions of anti-aggregation regulating material;

[0016] The ultrafine lightly calcined magnesium expansion material is lightly calcined magnesium oxide prepared by ultrafine grinding and suspension fluidized bed calcination and sorting processes. Its particle size range is 1~10μm, particle sphericity is ≥95%, and particle specific surface area is 1000~1100m². 2 / kg, with an active reaction time of 50s~75s;

[0017] The medium-fine light-burned magnesia-based expanded material is light-burned magnesia prepared by ultrafine grinding and suspension fluidized bed calcination and sorting processes. Its particle size ranges from 15 to 30 μm, with a sphericity ≥92% and a specific surface area of ​​550 to 600 m². 2 / kg, with an active reaction time of 120s~150s;

[0018] The medium-coarse calcareous expanded material is calcium oxide clinker powder obtained by grinding calcium oxide expanded clinker particles using a mechanical abrasive particle spheroidizer. Its particle size range is 30~100μm, particle sphericity ≥85%, and particle size specific surface area is 150~200m². 2 / kg, f-CaO content is 60%~65%;

[0019] The fly ash microspheres are air-classified ultrafine, globally shaped, dry-discharged fly ash microspheres with a particle size range of 0.1~2μm, a particle sphericity ≥99%, and a particle specific surface area of ​​1500~1800m². 2 / kg;

[0020] The nano-silica particles have a particle size range of 0.02~0.05μm, a sphericity ≥96%, and a specific surface area of ​​150,000~160,000 m². 2 / kg;

[0021] The anti-agglomeration regulating material is composed of zirconium aluminate coupling agent and hexadecyltrimethylammonium bromide in a weight ratio of 1:2 to 2:3.

[0022] Specifically, both the ultrafine light-burned magnesia expansion material and the medium-fine light-burned magnesia expansion material are prepared using magnesite powder with ≤10% residue on an 80μm sieve as raw material.

[0023] Furthermore, the preparation process of the ultrafine lightly calcined magnesia expanded material and the medium-fine lightly calcined magnesia expanded material includes:

[0024] (1) Magnesite powder and particle shaper are compounded together and then ground into magnesium oxide raw powder with a particle size of 30μm sieve residue ≤10% and particle sphericity ≥90% by an ultrafine grinding mill;

[0025] Preferably, the feed rate of the magnesite powder and particle shaping agent compound into the grinding mill is controlled at 10~15t / h, and the grinding time is controlled at 20~30min;

[0026] Preferably, the particle shaping agent is hexadecyltrimethoxysilane, and its dosage is calculated as 0.8% to 1.5% of the mass of magnesite powder;

[0027] (2) The magnesium oxide raw powder obtained in step (1) is subjected to gas-phase suspension fluidized shaping and calcination in a suspension fluidized boiling furnace. The calcination temperature is controlled between 800℃ and 860℃, and the calcination time is controlled between 10min and 15min. During the process of endothermic decomposition to generate lightly calcined magnesium oxide, the magnesium oxide raw powder is further fluidized and shaped to improve the sphericity of the particles by high-speed collision with the inner wall of the fluidized furnace in the gas-phase suspension state.

[0028] (3) After the magnesium oxide raw material powder is calcined by gas-phase suspension fluidization in a suspension fluidizing furnace, the difference in weight of lightly calcined magnesium oxide with different particle sizes is utilized to obtain ultrafine lightly calcined magnesium expanded material with a particle size range of 1~10μm and medium-fine lightly calcined magnesium expanded material with a particle size range of 15~30μm by classifying and sorting through a dust collector.

[0029] This invention uses magnesite powder as raw material and hexadecyltrimethoxysilane as a particle shaper. It utilizes an ionic surface modifier to generate micelles in a spherical microreactor, effectively controlling particle morphology and size during the ultrafine grinding of magnesite powder. This restricts the non-uniform growth and expansion of crystals, resulting in high sphericity, uniform particle size, and micron-level spherical magnesium oxide raw material powder. Furthermore, through gas-phase suspension fluidized bed calcination and weight difference sorting processes, ultrafine light-burned magnesia expansion materials and medium-fine light-burned magnesia expansion materials with high sphericity are prepared, exhibiting good ball bearing lubrication effects. This overcomes the characteristics of poor particle uniformity, numerous sharp edges, and high water absorption in light-burned magnesia prepared by existing processes, solving the problem of increased concrete viscosity caused by the high water absorption of light-burned magnesia.

[0030] Furthermore, the present invention also provides a method for preparing the above-mentioned crack-resistant rheologically modified functional material for steel plate-concrete composite cable towers, specifically including the following process steps:

[0031] (1) Ultrafine light-burned magnesia expansion materials and medium-fine light-burned magnesia expansion materials were prepared by ultrafine grinding and suspension fluidized calcination separation process;

[0032] (2) Medium-coarse calcium expanded materials were prepared by grinding calcium oxide expanded clinker particles using a mechanical abrasive particle spheroidizer;

[0033] (3) The ultrafine light-burned magnesia expansion material, the medium-fine light-burned magnesia expansion material, the medium-coarse calcareous expansion material, fly ash microspheres, nano silica and anti-agglomeration control material are put into a dry powder mixer in proportion to weight. The multi-scale powder particles are uniformly mixed by using a single-shaft plow-type forced stirring and an ultrasonic vibration dispersion process, thus obtaining the crack-resistant rheological modification functional material for the concrete of the ultra-high strength steel plate-concrete composite cable tower structure of the present invention.

[0034] Furthermore, the present invention also provides an application of the aforementioned crack-resistant rheological modified functional material for steel plate-concrete composite cable towers in the concrete of ultra-high strength steel plate-concrete composite cable tower structures.

[0035] The anti-cracking rheological modified functional material for steel plate-concrete composite cable towers described in this invention is used in the preparation of ultra-high strength concrete with other raw materials. The dosage of the anti-cracking rheological modified functional material accounts for 20% to 25% of the total mass of cementitious materials. First, the anti-cracking rheological modified functional material is pre-dry mixed with cement, fly ash, mineral powder, silica fume and sand for 10 to 15 seconds. Then, gravel, water and water-reducing agent are added and stirred for 100 to 150 seconds. The concrete prepared by this invention has the advantages of low viscosity, high anti-segregation and strong self-expansion ability. It is suitable for various high-strength self-compacting concrete construction conditions, especially for ultra-high strength steel plate-concrete composite cable tower structures where the inner wall of the steel plate is equipped with a large number of shear connectors such as studs and horizontal stiffening ribs, which hinder the flow of concrete.

[0036] (1) The shaped spheroidized modified light-burned magnesium expansion material in the anti-cracking rheological modified functional material of the present invention can overcome the problem that the light-burned magnesium oxide prepared by the existing process has a large wetting angle and strong water absorption, which leads to an increase in concrete viscosity. It can effectively reduce the viscosity of concrete by utilizing its own multi-spherical particle ball effect.

[0037] (2) Based on the shaping and spheroidizing modified light-burned magnesia expansion material and calcareous expansion material, this invention introduces finer spherical fly ash microspheres and ultrafine spherical nano silica. The submicron-sized fly ash microspheres and nano silica fill the pores of the light-burned magnesia expansion material and calcareous expansion material particles, thereby achieving a tight filling of spherical powder particles of different sizes and a ball bearing lubrication effect, further improving the viscosity reduction effect of the crack-resistant rheological modified functional material of this invention in concrete.

[0038] (3) This invention prepares ultrafine lightly calcined magnesia expansion material with a particle size range of 1~10μm and medium-fine lightly calcined magnesia expansion material with a particle size range of 15~30μm by sorting lightly calcined magnesia with different particle sizes based on their self-weight differences. These materials are then mixed evenly with medium-coarse calcareous expansion material with a particle size range of 30~100μm, fly ash microspheres with a particle size range of 0.1~2μm, and nano-silica with a particle size range of 0.02~0.05μm to form an optimized combination of multi-scale stepped spherical ultrafine powders. This achieves full coverage of fresh cement concrete paste and solves the problem of easy segregation and stratification of ultra-high strength concrete characterized by high powder content, low water-cement ratio, and low aggregate content.

[0039] (4) This invention achieves an optimized combination of ultrafine light-burned magnesia expansion material, medium-fine light-burned magnesia expansion material and medium-coarse calcareous expansion material, with ultrafine light-burned magnesia expansion material as the ultra-early expansion component, medium-coarse calcareous expansion material as the mid-term expansion component and medium-fine light-burned magnesia expansion material as the late expansion component. This overcomes the defect of mismatch in the process of calcium providing early expansion and magnesium providing mid-to-late expansion in the application of ultra-high strength concrete in the existing calcium-magnesia composite expansion technology. It solves the problem of large early autogenous shrinkage and rapid autogenous shrinkage development of ultra-high strength concrete, and matches the autogenous shrinkage development process of ultra-high strength concrete with low water-cement ratio and high powder content throughout the entire cycle.

[0040] (5) This invention utilizes an anti-agglomeration regulating component composed of zirconium aluminate coupling agent and cetyltrimethylammonium bromide to promote the uniformity of mixing of four raw material components of different particle sizes, namely magnesium-based expansion material, calcium-based expansion material, fly ash microspheres and nano-silica, under mechanical stirring and ultrasonic vibration. This improves the dispersibility and rheological properties of the multi-scale ultrafine powder composite material system. Moreover, each component has a synergistic effect under appropriate proportions, effectively reducing the viscosity of concrete and enhancing the self-expansion of concrete. This achieves the coordinated unity of rheological modification and viscosity reduction and self-expansion compensation for crack resistance in ultra-high strength concrete.

[0041] (6) The anti-cracking rheological modified functional material prepared by the present invention is simple to incorporate into ultra-high strength concrete and easy to operate. It can effectively reduce the viscosity of the slurry in the self-compacting grouting construction process of ultra-high strength concrete in steel plate-concrete composite cable tower structure, reduce the pitting phenomenon at local narrow gaps, and ensure the compactness of the concrete pouring of the inner wall of the steel plate with a large number of studs, horizontal stiffening ribs and other shear-resistant connectors. Detailed Implementation

[0042] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention. Unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods. Unless otherwise specified, the materials and reagents used in the embodiments of this invention are commercially available.

[0043] A crack-resistant rheological modification functional material for steel plate-concrete composite cable towers comprises the following components in parts by weight:

[0044] 25-35 parts of ultrafine lightly calcined magnesium expanded material

[0045] 18-25 parts of medium-fine light-burned magnesia-based expanded material

[0046] 20-30 parts of medium to coarse calcium expanded material,

[0047] 22-28 parts of fly ash microspheres

[0048] 10-15 parts of nano-silica

[0049] 1-3 portions of anti-aggregation regulating material;

[0050] The ultrafine lightly calcined magnesium expansion material is lightly calcined magnesium oxide prepared by ultrafine grinding and suspension fluidized bed calcination and sorting processes. Its particle size range is 1~10μm, particle sphericity is ≥95%, and particle specific surface area is 1000~1100m². 2 / kg, with an active reaction time of 50s~75s;

[0051] The medium-fine light-burned magnesia-based expanded material is light-burned magnesia prepared by ultrafine grinding and suspension fluidized bed calcination and sorting processes. Its particle size ranges from 15 to 30 μm, with a sphericity ≥92% and a specific surface area of ​​550 to 600 m². 2 / kg, with an active reaction time of 120s~150s;

[0052] The medium-coarse calcareous expanded material is calcium oxide clinker powder obtained by grinding calcium oxide expanded clinker particles using a mechanical abrasive particle spheroidizer. Its particle size range is 30~100μm, particle sphericity ≥85%, and particle size specific surface area is 150~200m². 2 / kg, f-CaO content is 60%~65%;

[0053] The fly ash microspheres are air-classified ultrafine, globally shaped, dry-discharged fly ash microspheres with a particle size range of 0.1~2μm, a particle sphericity ≥99%, and a particle specific surface area of ​​1500~1800m². 2 / kg;

[0054] The nano-silica particles have a particle size range of 0.02~0.05μm, a sphericity ≥96%, and a specific surface area of ​​150,000~160,000 m². 2 / kg;

[0055] The anti-agglomeration regulating material is composed of zirconium aluminate coupling agent and hexadecyltrimethylammonium bromide in a weight ratio of 1:2 to 2:3.

[0056] Specifically, both the ultrafine light-burned magnesia expansion material and the medium-fine light-burned magnesia expansion material are prepared using magnesite powder with ≤10% residue on an 80μm sieve as raw material.

[0057] Furthermore, the preparation process of the ultrafine lightly calcined magnesia expanded material and the medium-fine lightly calcined magnesia expanded material includes:

[0058] (1) Magnesite powder and particle shaper are compounded together and then ground into magnesium oxide raw powder with a particle size of 30μm sieve residue ≤10% and particle sphericity ≥90% by an ultrafine grinding mill;

[0059] Preferably, the feed rate of the magnesite powder and particle shaping agent compound into the grinding mill is controlled at 10~15t / h, and the grinding time is controlled at 20~30min;

[0060] Preferably, the particle shaping agent is hexadecyltrimethoxysilane, and its dosage is calculated as 0.8% to 1.5% of the mass of magnesite powder;

[0061] (2) The magnesium oxide raw powder obtained in step (1) is subjected to gas-phase suspension fluidized shaping and calcination in a suspension fluidized boiling furnace. The calcination temperature is controlled between 800℃ and 860℃, and the calcination time is controlled between 10min and 15min. During the process of endothermic decomposition to generate lightly calcined magnesium oxide, the magnesium oxide raw powder is further fluidized and shaped to improve the sphericity of the particles by high-speed collision with the inner wall of the fluidized furnace in the gas-phase suspension state.

[0062] (3) After the magnesium oxide raw material powder is calcined by gas-phase suspension fluidization in a suspension fluidizing furnace, the difference in weight of lightly calcined magnesium oxide with different particle sizes is utilized to obtain ultrafine lightly calcined magnesium expanded material with a particle size range of 1~10μm and medium-fine lightly calcined magnesium expanded material with a particle size range of 15~30μm by classifying and sorting through a dust collector.

[0063] Furthermore, the present invention also provides a method for preparing the above-mentioned crack-resistant rheologically modified functional material for steel plate-concrete composite cable towers, specifically including the following process steps:

[0064] (1) Ultrafine light-burned magnesia expansion materials and medium-fine light-burned magnesia expansion materials were prepared by ultrafine grinding and suspension fluidized calcination separation process;

[0065] (2) Medium-coarse calcium expanded materials were prepared by grinding calcium oxide expanded clinker particles using a mechanical abrasive particle spheroidizer;

[0066] (3) The ultrafine light-burned magnesia expansion material, the medium-fine light-burned magnesia expansion material, the medium-coarse calcareous expansion material, fly ash microspheres, nano silica and anti-agglomeration control material are put into a dry powder mixer in proportion to weight. The multi-scale powder particles are uniformly mixed by using a single-shaft plow-type forced stirring and an ultrasonic vibration dispersion process, thus obtaining the crack-resistant rheological modification functional material for the concrete of the ultra-high strength steel plate-concrete composite cable tower structure of the present invention.

[0067] Furthermore, the present invention also provides an application of the aforementioned crack-resistant rheology-modified functional material in the concrete of an ultra-high strength steel plate-concrete composite cable tower structure.

[0068] The crack-resistant rheological modified functional material of this invention is used in the preparation of ultra-high strength concrete together with other raw materials of concrete. The dosage accounts for 20% to 25% of the total mass of cementitious materials. First, the crack-resistant rheological modified functional material is pre-dry mixed with cement, fly ash, mineral powder, silica fume and sand for 10 to 15 seconds. Then, gravel, water and water-reducing agent are added and stirred for 100 to 150 seconds. Example 1

[0069] This embodiment describes a method for preparing a crack-resistant rheologically modified functional material for steel-concrete composite cable towers, comprising the following steps:

[0070] (1) 99.2% magnesite powder and 0.8% particle shaper were combined and fed into an ultrafine mill at a feed rate of 10t / h for 20min to prepare magnesium oxide raw powder with a sieve residue of 9% and a particle sphericity of 91% on a 30μm sieve.

[0071] (2) Magnesium oxide raw meal powder was calcined in a fluidized bed furnace at 800℃ for 12 min using a gas-phase suspension fluidization shaping method. Ultrafine light-burned magnesia expanded materials and medium-fine light-burned magnesia expanded materials were then prepared by classification and sorting using a dust collector. The ultrafine light-burned magnesia expanded materials had a particle sphericity of 95% and a specific surface area of ​​1100 m². 2 / kg, with an active reaction time of 50s, the sphericity of the medium-fine lightly calcined magnesia expanded material particles is 94%, and the specific surface area is 550m². 2 / kg, and the active reaction time is 120s;

[0072] (3) Calcium oxide clinker particles with an f-CaO content of 65% were ground in a mechanical abrasive particle spheroidizer to obtain particles with a sphericity of 86% and a specific surface area of ​​180 m². 2 / kg of medium-coarse calcium expanded material;

[0073] (4) The zirconium aluminate coupling agent and hexadecyltrimethylammonium bromide in a weight ratio of 1:2 are pre-composite to form an anti-agglomeration regulating component;

[0074] (5) 30 parts by weight of ultrafine light-burned magnesia expansion material, 25 parts by weight of medium-fine light-burned magnesia expansion material, 20 parts by weight of medium-coarse calcareous expansion material, 22 parts by weight of fly ash microspheres, 15 parts by weight of nano-silica and 2 parts by weight of anti-agglomeration control material are put into a dry powder mixer and mixed and homogenized for 3 minutes by single-axis plow-type forced stirring and ultrasonic vibration dispersion process to obtain the anti-cracking rheological modified functional material DE-1 of the present invention embodiment. Example 2

[0075] This embodiment describes a method for preparing a crack-resistant rheologically modified functional material for steel-concrete composite cable towers, comprising the following steps:

[0076] (1) 98.5% magnesite powder and 1.5% particle shaper were combined and fed into an ultrafine mill at a feed rate of 15t / h for 30min to prepare magnesium oxide raw powder with a sieve residue of 8.5% and a particle sphericity of 92% on a 30μm sieve.

[0077] (2) Magnesium oxide raw meal powder was calcined in a fluidized bed furnace at 860℃ for 15 min using a gas-phase suspension fluidization shaping method. Ultrafine light-burned magnesia expanded material and medium-fine light-burned magnesia expanded material were then prepared by classification and sorting using a dust collector. The ultrafine light-burned magnesia expanded material had a particle sphericity of 96% and a specific surface area of ​​1000 m². 2 / kg, with an active reaction time of 75s, the sphericity of the medium-fine lightly calcined magnesia expanded material particles is 95%, and the specific surface area is 600m². 2 / kg, and the active reaction time is 150s;

[0078] (3) Calcium oxide clinker particles with an f-CaO content of 60% were ground in a mechanical abrasive particle spheroidizer to obtain particles with a sphericity of 85% and a specific surface area of ​​150 m². 2 / kg of medium-coarse calcium expanded material;

[0079] (4) The zirconium aluminate coupling agent and hexadecyltrimethylammonium bromide in a weight ratio of 2:3 are pre-composite to form an anti-agglomeration regulating component;

[0080] (5) 25 parts by weight of ultrafine light-burned magnesia expansion material, 18 parts by weight of medium-fine light-burned magnesia expansion material, 20 parts by weight of medium-coarse calcareous expansion material, 28 parts by weight of fly ash microspheres, 15 parts by weight of nano-silica and 1 part by weight of anti-agglomeration control material are put into a dry powder mixer and mixed and homogenized for 3 minutes by single-axis plow-type forced stirring and ultrasonic vibration dispersion process to obtain the crack-resistant rheological modified functional material DE-2 of the present invention embodiment. Example 3

[0081] This embodiment describes a method for preparing a crack-resistant rheologically modified functional material for steel-concrete composite cable towers, comprising the following steps:

[0082] (1) 98.8% magnesite powder and 1.2% particle shaper were combined and fed into an ultrafine mill at a feed rate of 12t / h for 25min to prepare magnesium oxide raw powder with a sieve residue of 9.5% and a particle sphericity of 91% on a 30μm sieve.

[0083] (2) Magnesium oxide raw meal powder was calcined in a fluidized bed furnace at 825℃ for 10 min using a gas-phase suspension fluidization shaping method. Ultrafine light-burned magnesia expanded material and medium-fine light-burned magnesia expanded material were then prepared by classification and sorting using a dust collector. The ultrafine light-burned magnesia expanded material had a particle sphericity of 97% and a specific surface area of ​​1030 m². 2 / kg, with an active reaction time of 60s, the sphericity of the medium-fine lightly calcined magnesia expanded material particles is 95.5%, and the specific surface area is 580m². 2 / kg, and the active reaction time is 130s;

[0084] (3) Calcium oxide clinker particles with an f-CaO content of 63% were ground in a mechanical abrasive particle spheroidizer to obtain particles with a sphericity of 88% and a specific surface area of ​​200 m². 2 Medium-coarse calcium expanded material per kg.

[0085] (4) The zirconium aluminate coupling agent and hexadecyltrimethylammonium bromide in a weight ratio of 2:2 are pre-composite to form an anti-agglomeration regulating component;

[0086] (5) 35 parts by weight of ultrafine light-burned magnesia expansion material, 20 parts by weight of medium-fine light-burned magnesia expansion material, 30 parts by weight of medium-coarse calcareous expansion material, 25 parts by weight of fly ash microspheres, 10 parts by weight of nano-silica and 3 parts by weight of anti-agglomeration control material are put into a dry powder mixer and mixed and homogenized for 3 minutes by single-axis plow-type forced stirring and ultrasonic vibration dispersion process to obtain the crack-resistant rheological modified functional material DE-3 of the present invention embodiment.

[0087] Comparative Example 1

[0088] The preparation method of the crack-resistant rheology-modified functional material described in Comparative Example 1 includes:

[0089] (1) Magnesite powder was fed into an ultrafine mill at a feed rate of 10t / h and ultrafinely ground for 20min to prepare magnesium oxide raw powder with a sieve residue of 9.5% on a 30μm sieve.

[0090] (2) Magnesium oxide raw meal powder was calcined in a fluidized bed furnace at 800℃ for 12 min using a gas-phase suspension fluidization shaping method. The resulting material was then graded and sorted using a dust collector to obtain ultrafine light-burned magnesia expanded material and medium-fine light-burned magnesia expanded material. The ultrafine light-burned magnesia expanded material had a particle sphericity of 30% and a specific surface area of ​​1100 m². 2 / kg, with an active reaction time of 52s, the sphericity of the medium-fine lightly calcined magnesia expanded material particles is 22%, and the specific surface area is 560m². 2 / kg, and the active reaction time is 125s;

[0091] (3) Calcium oxide clinker particles with an f-CaO content of 65% were ground in a mechanical abrasive particle spheroidizer to obtain particles with a sphericity of 86% and a specific surface area of ​​180 m². 2 / kg of medium-coarse calcium expanded material;

[0092] (4) The zirconium aluminate coupling agent and hexadecyltrimethylammonium bromide in a weight ratio of 1:2 are pre-composite to form an anti-agglomeration regulating component;

[0093] (5) 30 parts by weight of ultrafine light-burned magnesia expansion material, 25 parts by weight of medium-fine light-burned magnesia expansion material, 20 parts by weight of medium-coarse calcareous expansion material, 22 parts by weight of fly ash microspheres, 15 parts by weight of nano-silica and 2 parts by weight of anti-agglomeration control material are put into a dry powder mixer and mixed and homogenized for 3 minutes by single-shaft plow-type forced stirring and ultrasonic vibration dispersion process to obtain the product of Comparative Example 1, a crack-resistant rheological modified functional material DB-1. Comparative Example 2

[0094] The raw materials and shaping and modification processes used in Example 1 are exactly the same as those used in Example 1. The only difference is that ultrafine light-burned magnesia expansion material is not added in the multi-component mixing and compounding process. Instead, 25 parts by weight of medium-fine light-burned magnesia expansion material, 20 parts by weight of medium-coarse calcareous expansion material, 22 parts by weight of fly ash microspheres, 15 parts by weight of nano-silica, and 2 parts by weight of anti-agglomeration regulating material are put into a dry powder mixer and mixed and homogenized for 3 minutes by a single-axis plow-type forced stirring and ultrasonic vibration dispersion process to obtain DB-2, a crack-resistant rheological modified functional material of Comparative Example 2 of the present invention. Comparative Example 3

[0095] The raw materials and shaping and modification processes used in Example 1 are exactly the same as those used in Example 1. The only difference is that no medium-fine light-burned magnesia expansion material is added in the multi-component mixing and compounding process. That is, 30 parts by weight of ultrafine light-burned magnesia expansion material, 20 parts by weight of medium-coarse calcareous expansion material, 22 parts by weight of fly ash microspheres, 15 parts by weight of nano-silica and 2 parts by weight of anti-agglomeration control material are put into a dry powder mixer and mixed and homogenized for 3 minutes by single-axis plow-type forced stirring and ultrasonic vibration dispersion process to obtain DB-3, a crack-resistant rheological modified functional material of Comparative Example 3 of the present invention. Comparative Example 4

[0096] The raw materials and shaping and modification processes used in Example 1 are exactly the same as those used in Example 1. The only difference is that no medium-coarse calcium expansion material is added in the multi-component mixing and compounding process. That is, 30 parts by weight of ultrafine light-burned magnesia expansion material, 25 parts by weight of medium-fine light-burned magnesia expansion material, 22 parts by weight of fly ash microspheres, 15 parts by weight of nano-silica and 2 parts by weight of anti-agglomeration control material are put into a dry powder mixer and mixed and homogenized for 3 minutes by single-axis plow-type forced stirring and ultrasonic vibration dispersion process to obtain DB-4, a crack-resistant rheological modified functional material of Comparative Example 4 of the present invention. Comparative Example 5

[0097] The raw materials and shaping and modification processes used in Example 1 are exactly the same as those used in Example 1. The only difference is that fly ash microspheres are not added in the multi-component mixing and compounding process. That is, 30 parts by weight of ultrafine light-burned magnesia expansion material, 25 parts by weight of medium-fine light-burned magnesia expansion material, 20 parts by weight of medium-coarse calcareous expansion material, 15 parts by weight of nano-silica and 2 parts by weight of anti-agglomeration control material are put into a dry powder mixer and mixed and homogenized for 3 minutes by single-axis plow-type forced stirring and ultrasonic vibration dispersion process to obtain DB-5, a crack-resistant rheological modified functional material of Comparative Example 5 of the present invention. Comparative Example 6

[0098] The raw materials and shaping and modification processes used in Example 1 are exactly the same as those used in Example 1. The only difference is that nano-silica is not added in the multi-component mixing and compounding process. That is, 30 parts by weight of ultrafine light-burned magnesia expansion material, 25 parts by weight of medium-fine light-burned magnesia expansion material, 20 parts by weight of medium-coarse calcareous expansion material, 22 parts by weight of fly ash microspheres and 2 parts by weight of anti-agglomeration control material are put into a dry powder mixer and mixed and homogenized for 3 minutes by single-axis plow-type forced stirring and ultrasonic vibration dispersion process to obtain DB-6, a crack-resistant rheological modified functional material of Comparative Example 6 of the present invention. Comparative Example 7

[0099] The raw materials and shaping and modification processes used in Example 1 are exactly the same as those used in Example 1. The only difference is that no anti-agglomeration control material is added in the multi-component mixing and compounding process. That is, 30 parts by weight of ultrafine light-burned magnesia expansion material, 25 parts by weight of medium-fine light-burned magnesia expansion material, 20 parts by weight of medium-coarse calcareous expansion material, 22 parts by weight of fly ash microspheres and 15 parts by weight of nano-silica are put into a dry powder mixer and mixed and homogenized for 3 minutes by a single-axis plow-type forced stirring and ultrasonic vibration dispersion process to obtain DB-7, a crack-resistant rheological modified functional material of Comparative Example 7 of the present invention. Comparative Example 8

[0100] Using commonly available unshaped and modified magnesium oxide and calcium oxide expanders as raw materials, ultrafine magnesium oxide expanders with a particle size range of 1–10 μm, medium-fine magnesium oxide expanders with a particle size range of 15–30 μm, and medium-coarse calcium oxide expanders with a particle size range of 30–100 μm were prepared by sieving. 30 parts by weight of ultrafine magnesium oxide expander, 25 parts by weight of medium-fine magnesium oxide expander, 20 parts by weight of medium-coarse calcium oxide expander, 22 parts by weight of fly ash microspheres, and 15 parts by weight of silica were added to a dry powder mixer and mixed and homogenized for 3 minutes using a single-axis plow-type forced stirring and ultrasonic vibration dispersion process to obtain DB-8, a crack-resistant rheological modified functional material of Comparative Example 8 of this invention.

[0101] Based on C80 self-compacting concrete used in the ultra-high strength steel plate-concrete composite cable tower structure of a certain bridge, the products prepared in Examples 1-3 and Comparative Examples 1-8 were incorporated into the concrete as crack-resistant rheological modification functional materials. The effects on concrete slump spread, pouring time, viscosity, segregation rate, and self-generated volumetric deformation under moisture were tested. The concrete mix design is shown in Table 1, where the cement is P.II 52.5 Portland cement, the initial setting time is 130 min, the final setting time is 210 min, and the specific surface area is 350 m². 2 / kg, 3-day compressive strength 36.4 MPa, 28-day compressive strength 60.8 MPa; fly ash is Class F, Grade I fly ash, water requirement ratio 93.5%, specific surface area 320 m² 2 / kg; the ore powder is S95 grade granulated blast furnace slag powder, with a flowability ratio of 104% and a specific surface area of ​​410m². 2 / kg; fine aggregate is medium sand of zone II with a fineness modulus of 2.6; coarse aggregate is basalt crushed stone with a continuous gradation of 5~20mm; water-reducing agent is polycarboxylate high-performance water-reducing agent.

[0102] Table 1 Concrete mix proportions (kg / m³) 3 )

[0103] serial number cement Mineral powder fly ash silica ash Cracking-resistant rheological modified functional materials sand pebbles Water reducing agent water Blank group 300 126 126 28 0 726 1002 9.8 142 Example 1 300 72 72 20 116 726 1002 8.5 142 Example 2 300 67 67 18 128 726 1002 8.5 142 Example 3 300 59 59 17 145 726 1002 8.5 142 Comparative Example 1 300 72 72 20 116 726 1002 8.7 142 Comparative Example 2 300 72 72 20 116 726 1002 8.5 142 Comparative Example 3 300 72 72 20 116 726 1002 8.5 142 Comparative Example 4 300 72 72 20 116 726 1002 8.5 142 Comparative Example 5 300 72 72 20 116 726 1002 8.5 142 Comparative Example 6 300 72 72 20 116 726 1002 8.5 142 Comparative Example 7 300 72 72 20 116 726 1002 8.5 142 Comparative Example 8 300 72 72 20 116 726 1002 8.9 142

[0104] According to the relevant provisions of the "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" (GB / T50080), the workability of C80 self-compacting concrete used in ultra-high strength steel plate-concrete composite cable tower structures was tested, including slump flow, inverted slump time, segregation rate, and air content. The viscosity of the concrete was tested using the inverted slump cylinder method. The shorter the time it takes for the concrete to flow out of the inverted slump cylinder, the lower the viscosity of the concrete. The plastic viscosity of the concrete was tested using a rheometer. The lower the plastic viscosity value, the lower the viscosity of the concrete. The test results are shown in Table 2.

[0105] Table 2 Test results of fresh concrete mix performance

[0106] serial number Sample Dosage Expansion / mm Rewinding time / s Plastic viscosity / mPa.s Separation rate / % Gas content / % Blank group 0 625 20.1 1.95 16.9 2.4 Example 1 20% 610 8.7 1.03 5.1 2.8 Example 2 22% 600 8.5 1.01 5.4 2.9 Example 3 25% 615 7.8 0.92 4.6 2.6 Comparative Example 1 20% 595 12.3 1.33 8.9 2.7 Comparative Example 2 20% 600 10.9 1.29 8.3 2.5 Comparative Example 3 20% 610 10.4 1.22 8.2 2.2 Comparative Example 4 20% 595 11.2 1.30 8.6 2.6 Comparative Example 5 20% 590 11.8 1.36 9.1 2.2 Comparative Example 6 20% 615 10.6 1.26 8.9 2.3 Comparative Example 7 20% 610 9.8 1.15 7.5 2.6 Comparative Example 8 20% 595 16.2 1.51 13.5 3.0

[0107] As can be seen from the data in Table 2, the slump expansion of the blank concrete without the anti-cracking rheological modification material, the application concrete with samples from Examples 1-3 of this invention, and the control concrete with samples from Comparative Examples 1-8 all remained within the range of 610±15mm. However, the pouring time of the application concrete with samples from Examples 1-3 of this invention was significantly shortened, the plastic viscosity index was significantly reduced, and the segregation rate was significantly reduced. This indicates that the ultra-high strength self-compacting concrete prepared with the anti-cracking rheological modification material of this invention has low viscosity and good anti-segregation properties.

[0108] In Comparative Example 1, no spheroidization and shaping modification was performed on the ultrafine light-burned magnesia-expanded material and the medium-fine light-burned magnesia-expanded material components. The number of spherical particles in the sample was significantly reduced, and the adsorption of water-reducing agent components was relatively high, which reduced the overall dispersion performance of concrete. As a result, the viscosity of the concrete paste was higher than that of the Example Group, and the segregation and stratification were more obvious.

[0109] Comparative Example 2 lacks the ultrafine lightly calcined magnesia-based expandable material component. Due to the absence of its ball-bearing effect, its performance in improving the viscosity and segregation of concrete paste is not as good as in the Example.

[0110] Comparative Example 3 lacks the medium-fine light-burned magnesia-based expansive material component. Due to the absence of its ball-bearing effect, its performance in improving the viscosity and segregation of concrete paste is not as good as that of the Example.

[0111] Comparative Example 4 lacks the medium-coarse calcareous expansive material component. Due to the absence of its ball-bearing effect, its performance in improving the viscosity and segregation of concrete paste is not as good as that of the Example.

[0112] Comparative Example 5 lacks fly ash microspheres, and due to the absence of the ball-bearing effect they bring, its performance in improving the viscosity and segregation of concrete paste is not as good as that of the Example.

[0113] Comparative Example 6 lacks nano-silica components, and due to the absence of the ball-bearing effect it brings, its performance in improving the viscosity and segregation of concrete paste is not as good as that of the Example.

[0114] Comparative Example 7 lacks anti-agglomeration regulating material components. Anti-agglomeration regulating material components have a certain dispersing and viscosity-reducing effect on concrete itself, so their performance in improving the viscosity and segregation of concrete paste is not as good as that of the Example.

[0115] In Comparative Example 8, unshaped modified magnesium oxide expansive agent and calcium oxide expansive agent were used to replace the three components of highly spherical ultrafine light-burned magnesium expansive material, medium-fine light-burned magnesium expansive material and medium-coarse calcium expansive material. This not only significantly reduced the spherical particles that had a ball-bearing lubrication effect, but also significantly increased the number of irregular calcium magnesium expansive material particles with multiple edges and corners. The slurry coating became worse, the amount of water-reducing agent increased, and the viscosity of the concrete slurry was higher than that of the Example Group, and the segregation and stratification were more obvious.

[0116] According to the relevant provisions of the test method for shrinkage of cement concrete in the "Test Procedures for Cement and Cement Concrete in Highway Engineering" (JTGE30), a Φ110mm×420mm cylindrical PVC pipe was used as a mold to cast concrete specimens inside the pipe. After the specimens were formed, a probe was embedded in the mold, the surface was smoothed, and then the mold was moved steadily into the shrinkage chamber and placed vertically on an iron frame with foam board for vibration damping. After the concrete initially set, the surface was sealed with paraffin wax, and a dial indicator was brought into contact with the embedded probe in the concrete. The dial indicator was fixed with an iron frame, and the changes in the dial indicator were recorded at the specified time. Taking the final setting of the concrete as the initial point, the autogenous volume deformation values ​​of different groups of concrete under sealed and moisture-free curing conditions at 20℃ were calculated. The calculation results are shown in Table 3.

[0117] Table 3. Results of autogenous volumetric deformation (µε) of concrete under 20℃ dry curing conditions.

[0118] serial number Sample Dosage 3d 7d 14d 28d 60d 90d Blank group 0 -93.2 -135.1 -174.0 -212.5 -270.3 -286.6 Example 1 20% 79.4 100.7 79.6 69.5 51.6 43.3 Example 2 22% 80.5 108.8 85.9 80.2 62.3 48.1 Example 3 25% 86.3 116.2 90.8 84.3 68.5 50.6 Comparative Example 1 20% 69.1 81.3 65.9 56.3 37.8 23.6 Comparative Example 2 20% 56.5 68.6 53.2 44.6 33.3 19.9 Comparative Example 3 20% 59.6 72.3 51.9 38.7 22.8 5.2 Comparative Example 4 20% 27.4 41.2 26.3 15.1 2.5 -13.7 Comparative Example 5 20% 72.1 82.8 68.3 56.3 40.9 30.6 Comparative Example 6 20% 71.5 80.6 65.1 53.7 38.2 27.7 Comparative Example 7 20% 75.5 89.8 73.2 63.1 46.4 38.9 Comparative Example 8 20% 50.3 56.2 23.8 -1.8 -41.1 -71.2

[0119] As can be seen from the data in Table 3, the blank group concrete without anti-cracking rheological modification materials exhibited continuous autogenous volume deformation under sealed and moisture-free curing conditions at 20℃, with autogenous shrinkage deformation reaching -286.6µε at 90 days.

[0120] The self-generated volumetric deformation of the concrete in the application group containing the samples of Examples 1-3 of this invention under moisture-free conditions all showed rapid expansion followed by slow shrinkage. The self-expansion deformation under moisture-free conditions reached its peak at 7 days, at 100.7µε, 108.8µε and 116.2µε respectively. After 14 days, the self-expansion deformation of the concrete under moisture-free conditions began to decrease slowly and shrink. At 90 days, the residual self-expansion deformation under moisture-free conditions was still as high as 43.3µε~50.6µε.

[0121] In Comparative Example 1, the ultrafine light-burned magnesia expansion material and the medium-fine light-burned magnesia expansion material components were not spheroidized and shaped. Although they still exhibited a certain degree of moisture-proof self-expansion effect under moisture-proof conditions, their moisture-proof self-expansion performance was not as good as that of the Example.

[0122] Comparative Examples 2-4 lacked ultrafine light-burned magnesia expansion material components, medium-fine light-burned magnesia expansion material components, and medium-coarse calcareous expansion material components, respectively. The lack of expansion components weakened the expansion driving force of the crack-resistant rheological modified functional material samples. Although a certain moisture-free self-expansion effect still occurred under moisture-free conditions, the moisture-free self-expansion performance was not as good as that of the examples. In particular, Comparative Example 4 lacked the medium-coarse calcareous expansion material component with high expansion efficiency. At 90 days, the moisture-free self-expansion deformation was exhausted and turned into self-shrinkage deformation of about -13.7µε.

[0123] Comparative Examples 5-7 lacked fly ash microspheres, nano-silica, and anti-agglomeration regulating materials, respectively. Although these ultrafine spherical powder particles do not produce a moisture-free self-expansion effect themselves, they can further enhance the self-expansion efficiency of calcium and magnesium expansion components under moisture-free curing conditions through the close complementary and synergistic filling effect of particles of different sizes. Therefore, the peak value of moisture-free self-expansion and the residual value at 90 days of age of the concrete in the control group lacking fly ash microspheres, nano-silica, and anti-agglomeration regulating materials are weaker than the corresponding values ​​of the concrete in the examples.

[0124] In Comparative Example 8, all three components of the spherical-shaped ultrafine light-burned magnesia expansion material, medium-fine light-burned magnesia expansion material, and medium-coarse calcium expansion material were replaced by unshaped modified magnesium oxide expansion agent and calcium oxide expansion agent. The early moisture-proof self-expansion efficiency was significantly reduced, and the self-expansion duration was shortened. At 28 days, the self-generated volume deformation of the concrete changed from the self-expansion state to the self-shrinkage state, and at 90 days, the self-shrinkage deformation reached -71.2µε.

[0125] A comprehensive comparison shows that the ultra-high strength self-compacting concrete prepared in Examples 1-3 of this invention has low viscosity, good anti-segregation and moisture-proof self-expansion properties. It can significantly improve the construction viscosity of the ultra-high strength steel plate-concrete composite cable tower structure, ensure the tight adhesion between the concrete and the inner wall of the steel plate, and achieve the coordinated unity of ultra-high strength concrete rheological modification to reduce viscosity and self-expansion to compensate for crack resistance.

Claims

1. A crack-resistant rheologically modified functional material for steel-concrete composite cable towers, characterized in that, The components are included in parts by weight as follows: 25-35 parts of ultrafine lightly calcined magnesium expanded material 18-25 parts of medium-fine light-burned magnesia-based expanded material 20-30 parts of medium to coarse calcium expanded material, 22-28 parts of fly ash microspheres 10-15 parts of nano-silica 1-3 portions of anti-aggregation regulating material; The ultrafine lightly calcined magnesium expansion material is lightly calcined magnesium oxide prepared by ultrafine grinding and suspension fluidized bed calcination and sorting processes. Its particle size range is 1~10μm, particle sphericity is ≥95%, and particle specific surface area is 1000~1100m². 2 / kg, with an active reaction time of 50s~75s; The medium-fine light-burned magnesia-based expanded material is light-burned magnesia prepared by ultrafine grinding and suspension fluidized bed calcination and sorting processes. Its particle size ranges from 15 to 30 μm, with a sphericity ≥92% and a specific surface area of ​​550 to 600 m². 2 / kg, with an active reaction time of 120s~150s; The medium-coarse calcareous expanded material is calcium oxide clinker powder obtained by grinding calcium oxide expanded clinker particles using a mechanical abrasive particle spheroidizer. Its particle size range is 30~100μm, particle sphericity ≥85%, and particle size specific surface area is 150~200m². 2 / kg, f-CaO content is 60%~65%; The fly ash microspheres are air-classified ultrafine, globally shaped, dry-discharged fly ash microspheres with a particle size range of 0.1~2μm, a particle sphericity ≥99%, and a particle specific surface area of ​​1500~1800m². 2 / kg; The nano-silica particles have a particle size range of 0.02~0.05μm, a sphericity ≥96%, and a specific surface area of ​​150,000~160,000 m². 2 / kg; The anti-agglomeration regulating material is composed of zirconium aluminate coupling agent and hexadecyltrimethylammonium bromide in a weight ratio of 1:2 to 2:

3.

2. The crack-resistant rheological modified functional material for steel-concrete composite cable towers according to claim 1, characterized in that, Both the ultrafine light-burned magnesia expansion material and the medium-fine light-burned magnesia expansion material are prepared using magnesite powder with ≤10% residue on an 80μm sieve as raw material.

3. The crack-resistant rheologically modified functional material for steel-concrete composite cable towers according to claim 2, characterized in that, The preparation processes for the ultrafine lightly calcined magnesia-based expanded materials and the medium-fine lightly calcined magnesia-based expanded materials include: (1) Magnesite powder and particle shaper are compounded together and then ground into magnesium oxide raw powder with a particle size of 30μm sieve residue ≤10% and particle sphericity ≥90% by an ultrafine grinding mill; (2) The magnesium oxide raw powder obtained in step (1) is subjected to gas-phase suspension fluidized bed calcination in a suspension fluidized bed furnace. The calcination temperature is controlled between 800℃ and 860℃, and the calcination time is controlled between 10min and 15min. (3) After the magnesium oxide raw material powder is calcined by gas-phase suspension fluidization in a suspension fluidizing furnace, it is classified and sorted by a dust collector to obtain ultrafine light-burned magnesium expanded material with a particle size range of 1~10μm and medium-fine light-burned magnesium expanded material with a particle size range of 15~30μm.

4. The crack-resistant rheologically modified functional material for steel-concrete composite cable towers according to claim 3, characterized in that, In step (1), the feed rate of the magnesite powder and particle shaping agent compound into the grinding mill is controlled at 10~15t / h, and the grinding time is controlled at 20~30min. The particle shaping agent is hexadecyltrimethoxysilane, and its dosage is calculated as 0.8% to 1.5% of the mass of magnesite powder.

5. A method for preparing a crack-resistant rheologically modified functional material for steel-concrete composite cable towers according to any one of claims 1 to 4, characterized in that, Specifically, the process steps include the following: (1) Ultrafine light-burned magnesia expansion materials and medium-fine light-burned magnesia expansion materials were prepared by ultrafine grinding and suspension fluidized calcination separation process; (2) Medium-coarse calcium expanded materials were prepared by grinding calcium oxide expanded clinker particles using a mechanical abrasive particle spheroidizer; (3) The ultrafine light-burned magnesia expansion material, the medium-fine light-burned magnesia expansion material, the medium-coarse calcareous expansion material, fly ash microspheres, nano silica and anti-agglomeration control material are put into a dry powder mixer in proportion to weight. The multi-scale powder particles are uniformly mixed by using a single-shaft plow-type forced stirring and an ultrasonic vibration dispersion process to obtain the anti-cracking rheological modified functional material for steel plate-concrete composite cable tower.

6. The application of the anti-cracking rheological modified functional material for steel plate-concrete composite cable towers as described in any one of claims 1 to 4 in the concrete of ultra-high strength steel plate-concrete composite cable tower structures.

7. The application according to claim 6, characterized in that, Specifically, it includes: First, dry mix the crack-resistant rheology-modified functional material with cement, fly ash, mineral powder, silica fume and sand for 10s~15s, then add gravel, water and water-reducing agent and mix for 100s~150s. The amount of the crack-resistant rheology-modified functional material is 20% to 25% of the total mass of the cementitious material.